Forces (terminal velocity, moments, elasticity) Flashcards

1
Q

What do resultant forces cause (2)

A

Change in shape

Change in their motion

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2
Q

What does an object that is not changing motion or shape experience

A

No resultant force

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3
Q

What are forces so what do they have

A

Vectors, so have a magnitude (size e.g. 10 newtons) and a direction

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4
Q

What are scalers

A

Not vectors, they are quantities that only have a magnitude e.g. length, area, mass, time

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5
Q

What must you look at to find the resultant force

A

Size and direction

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6
Q

What is Newton’s first law

A

If the resultant force acts on an object then that object will accelerate
So if there are a number of forces on an object but the resultant force is 0N then there will be no change in motion

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7
Q

What is Newton’s second law

A

Resultant force = mass x acceleration

F = m x a

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8
Q

What happens if the resultant force is in the direction of motion in an object

A

It will accelerate

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9
Q

What happens if the resultant force is opposing the motion of an object

A

It will decelerate

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10
Q

What does friction oppose

A

Motion

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11
Q

What is the equation that links gravitational pull, weight and mass

A

w = m x g

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12
Q

What is terminal velocity

A

The maximum constant speed of an object as the resistance is preventing it from accelerating any further

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13
Q

How does an object reach its terminal velocity

A

As an object falls it accelerates

As the object falls and gets faster the resistive force increases

Acceleration starts to decrease as the resultant force is getting less

At a certain speed the resistance and the weight will eventually be equal so the forces are balanced and the object is no longer accelerating

The object continues to fall but at a constant speed which is called its terminal velocity

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14
Q

How can we increase the terminal velocity

A

Make the object more aerodynamic or streamlined so resistance is reduced

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15
Q

What is a moment

A

It is the turning effect caused by a force

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16
Q

What is a pivot point

A

A point which the object can turn about when a force is applied

17
Q

When are bigger moments created (2)

A

The force causing the effect is larger

The perpendicular distance from the pivot point is increased

18
Q

What is the equation for moments

A

Moment = force x perpendicular distance

19
Q

What are moments

A

Vectors, they have a magnitude and a direction

20
Q

What causes the direction of movement during a moment

A

The direction of the turning effect

21
Q

What is the principle of moments

A

The object is balanced (in equilibrium) so all the anti-clockwise moments added together are equal to all the clockwise moments added together

22
Q

What is the centre of mass

A

The point at which all the mass of an object appears to be

23
Q

What determines the stability of an object (2)

A

The centre of gravity

The length of base

24
Q

What is stability

A

It is the measure of how far an object can be displaced from its resting position and still return when released instead of toppling

25
Q

When will an object return back to its resting position

A

When the weight arrow falls within the case as it will experience an anti-clockwise moment

26
Q

When will an object topple over

A

When the weight arrow is past the base so it experiences a clockwise moment

27
Q

What is an elastic material

A

If a material returns to its original shape once a deforming force is removed it is said to be elastic

28
Q

What is a plastic material

A

If a material is permanently deformed when a force is applied it is plastic

29
Q

What is Hooke’s Law

A

When the extension of an object is directly proportional to the force applied to it

30
Q

How do we calculate the applied force

A

w = m x g

31
Q

How do we calculate extension

A

Total new length - original length

32
Q

What is the equation for Hooke’s Law

A

Force is directly proportional to extension F 🐟 x

F = kx

F means force
k means the constant, so how stiff the material is (how much force for a certain extension)
x means is the extension

33
Q

Why is a rubber band not obey Hooke’s law

A

The force and extension are not directly proportional as the lines on the graph are not straight